APACHE SERVER 2.2 for Unix

U_Apache_2-2_Server_UNIX_V1R6_Manual-xccdf.xml

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V1R6

2014-12-05

Update existing CKLs to this version of the STIG

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All directives specified in this STIG must be specifically set (i.e. the server is not allowed to revert to programmed defaults for these directives).
Included files should be reviewed if they are used. Procedures for reviewing included files are included in the overview document.
The use of .htaccess files are not authorized for use according to the STIG. However, if they are used, there are procedures for reviewing them in the overview document.
The Web Policy STIG should be used in addition to the Apache Site and Server STIGs in order to do a comprehensive web server review.

Vuln

Rule

Version

CCI

Severity

Title

Description

SV-36309r2_rule

WG370 A22

MEDIUM

MIME types for csh or sh shell programs must be disabled.

Users must not be allowed to access the shell programs. Shell programs might execute shell escapes and could then perform unauthorized activities that could damage the security posture of the web server. A shell is a program that serves as the basic interface between the user and the operating system. In this regard, there are shells that are security risks in the context of a web server and shells that are unauthorized in the context of the Security Features User's Guide.System AdministratorWeb AdministratorECSC-1

SV-6930r1_rule

WG420 A22

LOW

Backup interactive scripts on the production web server are prohibited.

Copies of backup files will not execute on the server, but they can be read by the anonymous user if special precautions are not taken. Such backup copies contain the same sensitive information as the actual script being executed and, as such, are useful to malicious users. Techniques and systems exist today that search web servers for such files and are able to exploit the information contained in them.
Backup copies of files are automatically created by some text editors such as emacs and edit plus. The emacs editor will write a backup file with an extension ~ added to the name of the original file. The edit plus editor will create a .bak file. Of course, this would imply the presence and use of development tools on the web server, which is a finding under WG130. Having backup scripts on the web server provides one more opportunity for malicious persons to view these scripts and use the information found in them.
System AdministratorWeb AdministratorECSC-1

SV-32788r1_rule

WG050 A22

MEDIUM

The web server password(s) must be entrusted to the SA or Web Manager.

Normally, a service account is established for the web server. This is because a privileged account is not desirable and the server is designed to run for long uninterrupted periods of time. The SA or Web Manager will need password access to the web server to restart the service in the event of an emergency as the web server is not to restart automatically after an unscheduled interruption. If the password is not entrusted to an SA or web manager the ability to ensure the availability of the web server is compromised.System AdministratorInformation Assurance OfficerWeb AdministratorIAAC-1

SV-32957r1_rule

WG040 A22

MEDIUM

Public web server resources must not be shared with private assets.

It is important to segregate public web server resources from private resources located behind the DoD DMZ in order to protect private assets. When folders, drives or other resources are directly shared between the public web server and private servers the intent of data and resource segregation can be compromised.
In addition to the requirements of the DoD Internet-NIPRNet DMZ STIG that isolates inbound traffic from the external network to the internal network, resources such as printers, files, and folders/directories will not be shared between public web servers and assets located within the internal network.
Web AdministratorEBPW-1

SV-32956r2_rule

WG080 A22

MEDIUM

Installation of a compiler on production web server is prohibited.

The presence of a compiler on a production server facilitates the malicious user’s task of creating custom versions of programs and installing Trojan Horses or viruses. For example, the attacker’s code can be uploaded and compiled on the server under attack.Web AdministratorECSC-1

SV-32932r2_rule

WA060 A22

MEDIUM

A public web server, if hosted on the NIPRNet, must be isolated in an accredited DoD DMZ Extension.

To minimize exposure of private assets to unnecessary risk by attackers, public web servers must be isolated from internal systems. Public web servers are by nature more vulnerable to attack from publically based sources, such as the public Internet. Once compromised, a public web server might be used as a base for further attack on private resources, unless additional layers of protection are implemented. Public web servers must be located in a DoD DMZ Extension, if hosted on the NIPRNet, with carefully controlled access. Failure to isolate resources in this way increase risk that private assets are exposed to attacks from public sources.System AdministratorInformation Assurance OfficerEBPW-1, ECIC-1

SV-32935r1_rule

WA070 A22

MEDIUM

A private web server must be located on a separate controlled access subnet.

Private web servers, which host sites that serve controlled access data, must be protected from outside threats in addition to insider threats. Insider threat may be accidental or intentional but, in either case, can cause a disruption in service of the web server. To protect the private web server from these threats, it must be located on a separate controlled access subnet and must not be a part of the public DMZ that houses the public web servers. It also cannot be located inside the enclave as part of the local general population LAN.System AdministratorInformation Assurance OfficerEBPW-1

SV-36441r1_rule

WG190 A22

HIGH

Web server software must be a vendor-supported version.

Many vulnerabilities are associated with older versions of web server software. As hot fixes and patches are issued, these solutions are included in the next version of the server software. Maintaining the web server at a current version makes the efforts of a malicious user to exploit the web service more difficult.System AdministratorWeb AdministratorECSC-1

SV-36456r1_rule

WG200 A22

HIGH

Administrators must be the only users allowed access to the directory tree, the shell, or other operating system functions and utilities.

As a rule, accounts on a web server are to be kept to a minimum. Only administrators, web managers, developers, auditors, and web authors require accounts on the machine hosting the web server. This is in addition to the anonymous web user account. The resources to which these accounts have access must also be closely monitored and controlled. Only the SA needs access to all the system’s capabilities, while the web administrator and associated staff require access and control of the web content and web server configuration files. The anonymous web user account must not have access to system resources as that account could then control the server.System AdministratorWeb AdministratorECLP-1

SV-32948r1_rule

WG220 A22

MEDIUM

Web administration tools must be restricted to the web manager and the web manager’s designees.

All automated information systems are at risk of data loss due to disaster or compromise. Failure to provide adequate protection to the administration tools creates risk of potential theft or damage that may ultimately compromise the mission. Adequate protection ensures that server administration operates with less risk of losses or operations outages. The key web service administrative and configuration tools must be accessible only by the authorized web server administrators. All users granted this authority must be documented and approved by the IAO. Access to the IIS Manager will be limited to authorized users and administrators. System AdministratorWeb AdministratorECCD-1, ECCD-2, ECLP-1

SV-32955r1_rule

WG130 A22

LOW

All utility programs, not necessary for operations, must be removed or disabled.

Just as running unneeded services and protocols is a danger to the web server at the lower levels of the OSI model, running unneeded utilities and programs is also a danger at the application layer of the OSI model. Office suites, development tools, and graphical editors are examples of such programs that are troublesome. Individual productivity tools have no legitimate place or use on an enterprise, production web server and they are also prone to their own security risks.
Web AdministratorECSC-1

In addition to OS restrictions, access rights to files and directories can be set on a web site using the web server software. That is, in addition to allowing or denying all access rights, a rule can be specified that allows or denies partial access rights. For example, users can be given read-only access rights to files, to view the information but not change the files.
This check verifies that the htpasswd file is only accessible by system administrators or web managers, with the account running the web service having group permissions of read and execute. htpasswd is a utility used by Netscape and Apache to provide for password access to designated web sites. ISystem AdministratorWeb AdministratorECAN-1

SV-6880r1_rule

WG280

MEDIUM

The access control files are owned by a privileged web server account.

This check verifies that the key web server system configuration files are owned by the SA or Web Manager controlled account. These same files which control the configuration of the web server, and thus its behavior, must also be accessible by the account which runs the web service. If these files are altered by a malicious user, the web server would no longer be under the control of its managers and owners; properties in the web server configuration could be altered to compromise the entire server platform.
System AdministratorWeb AdministratorECCD-1, ECCD-2

SV-32951r1_rule

WA120 A22

LOW

Administrative users and groups that have access rights to the web server must be documented.

There are typically several individuals and groups that are involved in running a production web server. These accounts must be restricted to only those necessary to maintain web services, review the server’s operation, and the operating system. By minimizing the amount of user and group accounts on a web server the total attack surface of the server is minimized. Additionally, if the required accounts aren’t documented no known standard is created. Without a known standard the ability to identify required accounts is diminished, increasing the opportunity for error when such a standard is needed (i.e. COOP, IR, etc.).System AdministratorInformation Assurance ManagerWeb AdministratorECPA-1

This check verifies that the key web server system configuration files are owned by the SA or the web administrator controlled account. These same files that control the configuration of the web server, and thus its behavior, must also be accessible by the account that runs the web service. If these files are altered by a malicious user, the web server would no longer be under the control of its managers and owners; properties in the web server configuration could be altered to compromise the entire server platform.Web AdministratorECCD-1, ECCD-2, ECLP-1

SV-32937r1_rule

WG330 A22

MEDIUM

A public web server must limit email to outbound only.

Incoming E-mail has been known to provide hackers with access to servers. Disabling the incoming mail service prevents this type of attacks. Additionally, Email represents the main use of the Internet. It is specialized application that requires the dedication of server resources. To combine this type of transaction processing function with the file serving role of the web server creates an inherent conflict. Supporting mail services on a web server opens the server to the risk of abuse as an email relay.
Web AdministratorECSC-1

SV-32927r1_rule

WG440 A22

MEDIUM

Monitoring software must include CGI or equivalent programs in its scope.

By their very nature, CGI type files permit the anonymous web user to interact with data and perhaps store data on the web server. In many cases, CGI scripts exercise system-level control over the server’s resources. These files make appealing targets for the malicious user. If these files can be modified or exploited, the web server can be compromised. These files must be monitored by a security tool that reports unauthorized changes to these files.
Web AdministratorECAT-1, ECAT-2, ECCD-1

SV-32964r1_rule

WA140 A22

LOW

Web server content and configuration files must be part of a routine backup program.

Backing up web server data and web server application software after upgrades or maintenance ensures that recovery can be accomplished up to the current version. It also provides a means to determine and recover from subsequent unauthorized changes to the software and data.
A tested and verifiable backup strategy will be implemented for web server software as well as all web server data files. Backup and recovery procedures will be documented and the Web Manager or SA for the specific application will be responsible for the design, test, and implementation of the procedures.
The site will have a contingency processing plan/disaster recovery plan that includes web servers. The contingency plan will be periodically tested in accordance with DoDI 8500.2 requirements.
The site will identify an off-site storage facility in accordance with DoDI 8500.2 requirements. Off-site backups will be updated on a regular basis and the frequency will be documented in the contingency plan.
System AdministratorInformation Assurance OfficerWeb AdministratorCODB-1, CODB-2, CODB-3

SV-32950r1_rule

WG204 A22

MEDIUM

A web server must be segregated from other services.

The web server installation and configuration plan should not support the co-hosting of multiple services such as Domain Name Service (DNS), e-mail, databases, search engines, indexing, or streaming media on the same server that is providing the web publishing service. By separating these services additional defensive layers are established between the web service and the applicable application should either be compromised.
Disallowed or restricted services in the context of this vulnerability applies to services that are not directly associated with the delivery of web content. An operating system that supports a web server will not provide other services (e.g., domain controller, e-mail server, database server, etc.). Only those services necessary to support the web server and its hosted sites are specifically allowed and may include, but are not limited to, operating system, logging, anti-virus, host intrusion detection, administrative maintenance, or network requirements.
Web AdministratorDCPA-1

SV-36672r1_rule

WG520 A22

LOW

Web server and/or operating system information must be protected.

The web server response header of an HTTP response can contain several fields of information including the requested HTML page. The information included in this response can be web server type and version, operating system and version, and ports associated with the web server. This provides the malicious user valuable information without the use of extensive tools.System AdministratorWeb AdministratorECSC-1

SV-32969r1_rule

WA230 A22

MEDIUM

The Web site software used with the web server must have all applicable security patches applied and documented.

The IAVM process does not address all patches that have been identified for the host operating system or, in this case, the web server software environment. Many vendors have subscription services available to notify users of known security threats. The site needs to be aware of these fixes and make determinations based on local policy and what software features are installed, if these patches need to be applied.
In some cases, patches also apply to middleware and database systems. Maintaining the security of web servers requires frequent reviews of security notices. Many security notices mandate the installation of a software patch to overcome security vulnerabilities.
SAs and IAOs should regularly check the vendor support web site for patches and information related to the web server software. All applicable security patches will be applied to the operating system and to the web server software. Security patches are deemed applicable if the product is installed, even if it is not used or is disabled.
Information Assurance OfficerECSC-1

SV-32936r1_rule

WG355 A22

MEDIUM

A private web server’s list of CAs in a trust hierarchy must lead to an authorized DoD PKI Root CA.

A PKI certificate is a digital identifier that establishes the identity of an individual or a platform. A server that has a certificate provides users with third-party confirmation of authenticity. Most web browsers perform server authentication automatically and the user is notified only if the authentication fails. The authentication process between the server and the client is performed using the SSL/TLS protocol. Digital certificates are authenticated, issued, and managed by a trusted Certificate Authority (CA).
The use of a trusted certificate validation hierarchy is crucial to the ability to control access to a site’s server and to prevent unauthorized access. Only DoD-approved PKIs will be utilized.
Information Assurance OfficerWeb AdministratorIATS-1, IATS-2

SV-32933r1_rule

WG385 A22

HIGH

All web server documentation, sample code, example applications, and tutorials must be removed from a production web server.

Web server documentation, sample code, example applications, and tutorials may be an exploitable threat to a web server. A production web server may only contain components that are operationally necessary (e.g., compiled code, scripts, web-content, etc.). Delete all directories that contain samples and any scripts used to execute the samples. If there is a requirement to maintain these directories at the site on non-production servers for training purposes, have NTFS permissions set to only allow access to authorized users (i.e., web administrators and systems administrators). Sample applications or scripts have not been evaluated and approved for use and may introduce vulnerabilities to the system.Any sample application or sample executable script found on the production web server will be a CAT I finding.
Any web server documentation or sample file found on the production web server and accessible to web users or non-administrators will be a CAT III finding.
Any web server documentation or sample file found on the production web server and accessible only to SAs or to web administrators is permissible and not a finding.
Information Assurance OfficerWeb AdministratorECSC-1

SV-32954r1_rule

WG145 A22

MEDIUM

The private web server must use an approved DoD certificate validation process.

Without the use of a certificate validation process, the site is vulnerable to accepting certificates that have expired or have been revoked. This would allow unauthorized individuals access to the web server. This also defeats the purpose of the multi-factor authentication provided by the PKI process.
Web AdministratorIATS-1, IATS-2

SV-32977r1_rule

WA000-WWA020 A22

MEDIUM

The Timeout directive must be properly set.

The Timeout requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.Web AdministratorECSC-1

SV-32844r1_rule

WA000-WWA022 A22

MEDIUM

The KeepAlive directive must be enabled.

The KeepAlive extension to HTTP/1.0 and the persistent connection feature of HTTP/1.1 provide long lived HTTP sessions which allow multiple requests to be sent over the same connection. These requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.Web AdministratorECSC-1

SV-32877r1_rule

WA000-WWA024 A22

MEDIUM

The KeepAliveTimeout directive must be defined.

The number of seconds Apache will wait for a subsequent request before closing the connection. Once a request has been received, the timeout value specified by the Timeout directive applies. Setting KeepAliveTimeout to a high value may cause performance problems in heavily loaded servers. The higher the timeout, the more server processes will be kept occupied waiting on connections with idle clients. These requirements are set to mitigate the effects of several types of denial of service attacks. Web AdministratorECSC-1

SV-36645r1_rule

WA000-WWA026 A22

MEDIUM

The httpd.conf StartServers directive must be set properly.

These requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.
From Apache.org: The StartServers directive sets the number of child server processes created on startup. As the number of processes is dynamically controlled depending on the load, there is usually little reason to adjust this parameter.
The default value differs from MPM to MPM. For worker the default is StartServers 3. For prefork defaults to 5 and for mpmt_os2 to 2.Web AdministratorECSC-1

SV-36646r1_rule

WA000-WWA028 A22

MEDIUM

The httpd.conf MinSpareServers directive must be set properly.

These requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.
From Apache.org: The MinSpareServers directive sets the desired minimum number of idle child server processes. An idle process is one which is not handling a request. If there are fewer than MinSpareServers idle, then the parent process creates new children at a maximum rate of 1 per second.
Tuning of this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always a bad idea.Web AdministratorECSC-1

SV-36648r1_rule

WA000-WWA030 A22

LOW

The httpd.conf MaxSpareServers directive must be set properly.

These requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.
From Apache.org:The MaxSpareServers directive sets the desired maximum number of idle child server processes. An idle process is one which is not handling a request. If there are more than MaxSpareServers idle, then the parent process will kill off the excess processes.
Tuning of this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always a bad idea. If you are trying to set the value equal to or lower than MinSpareServers, Apache will automatically adjust it to MinSpareServers + 1.Web AdministratorECSC-1

SV-36649r1_rule

WA000-WWA032 A22

MEDIUM

The httpd.conf MaxClients directive must be set properly.

These requirements are set to mitigate the effects of several types of denial of service attacks. Although there is some latitude concerning the settings themselves, the requirements attempt to provide reasonable limits for the protection of the web server. If necessary, these limits can be adjusted to accommodate the operational requirement of a given system.
From Apache.org: The MaxClients directive sets the limit on the number of simultaneous requests that will be served. Any connection attempts over the MaxClients limit will normally be queued, up to a number based on the ListenBacklog directive. Once a child process is freed at the end of a different request, the connection will then be serviced.
For non-threaded servers (i.e., prefork), MaxClients translates into the maximum number of child processes that will be launched to serve requests. The default value is 256; to increase it, you must also raise ServerLimit.
For threaded and hybrid servers (e.g. beos or worker) MaxClients restricts the total number of threads that will be available to serve clients. The default value for beos is 50. For hybrid MPMs the default value is 16 (ServerLimit) multiplied by the value of 25 (ThreadsPerChild). Therefore, to increase MaxClients to a value that requires more than 16 processes, you must also raise ServerLimit.Web AdministratorECSC-1

SV-32763r1_rule

WA000-WWA050 A22

MEDIUM

All interactive programs must be placed in a designated directory with appropriate permissions.

Directory options directives are directives that can be applied to further restrict access to file and directories. The Options directive controls which server features are available in a particular directory. The ExecCGI option controls the execution of CGI scripts using mod_cgi. This needs to be restricted to only the directory intended for script execution.Web AdministratorECSC-1

SV-40129r1_rule

WA000-WWA052 A22

MEDIUM

The "–FollowSymLinks” setting must be disabled.

The Options directive configures the web server features that are available in particular directories. The FollowSymLinks option controls the ability of the server to follow symbolic links. A symbolic link allows a file or a directory to be referenced using a symbolic name raising a potential hazard if symbolic linkage is made to a sensitive area. When web scripts are executed and symbolic links are allowed, the web user could be allowed to access locations on the web server that are outside the scope of the web document root or home directory.Web AdministratorECSC-1

SV-32753r1_rule

WA000-WWA054 A22

HIGH

Server side includes (SSIs) must run with execution capability disabled.

The Options directive configures the web server features that are available in particular directories. The IncludesNOEXEC feature controls the ability of the server to utilize SSIs while disabling the exec command, which is used to execute external scripts. If the full includes feature is used it could allow the execution of malware leading to a system compromise. Web AdministratorECSC-1

SV-32754r1_rule

WA000-WWA056 A22

MEDIUM

The MultiViews directive must be disabled.

Directory options directives are directives that can be applied to further restrict access to file and directories. MultiViews is a per-directory option, meaning it can be set with an Options directive within a , or section in httpd.conf, or (if AllowOverride is properly set) in .htaccess files. The effect of MultiViews is as follows: if the server receives a request for /some/dir/foo, if /some/dir has MultiViews enabled, and /some/dir/foo does not exist, then the server reads the directory looking for files named foo.*, and effectively fakes up a type map which names all those files, assigning them the same media types and content-encodings it would have if the client had asked for one of them by name. It then chooses the best match to the client's requirements.Web AdministratorECSC-1

SV-32755r1_rule

WA000-WWA058 A22

MEDIUM

Directory indexing must be disabled on directories not containing index files.

Directory options directives are directives that can be applied to further restrict access to file and directories. If a URL which maps to a directory is requested, and there is no DirectoryIndex (e.g., index.html) in that directory, then mod_autoindex will return a formatted listing of the directory which is not acceptable.Web AdministratorECSC-1

SV-32756r1_rule

WA000-WWA060 A22

MEDIUM

The HTTP request message body size must be limited.

Buffer overflow attacks are carried out by a malicious attacker sending amounts of data that the web server cannot store in a given size buffer. The eventual overflow of this buffer can overwrite system memory. Subsequently an attacker may be able to elevate privileges and take control of the server. The Apache directives listed below limit the size of the various HTTP header sizes thereby limiting the chances for a buffer overflow.
The LimitRequestBody directive allows the user to set a limit on the allowed size of an HTTP request message body within the context in which the directive is given (server, per-directory, per-file or per-location). If the client request exceeds that limit, the server will return an error response instead of servicing the request. The size of a normal request message body will vary greatly depending on the nature of the resource and the methods allowed on that resource. CGI scripts typically use the message body for retrieving form information. Implementations of the PUT method will require a value at least as large as any representation that the server wishes to accept for that resource.
Web AdministratorECSC-1

SV-32757r1_rule

WA000-WWA062 A22

MEDIUM

The HTTP request header fields must be limited.

Buffer overflow attacks are carried out by a malicious attacker sending amounts of data that the web server cannot store in a given size buffer. The eventual overflow of this buffer can overwrite system memory. Subsequently an attacker may be able to elevate privileges and take control of the server. This Apache directives limits the size of the various HTTP header sizes thereby limiting the chances for a buffer overflow.
The LimitRequestFields directive allows the server administrator to modify the limit on the number of request header fields allowed in an HTTP request. A server needs this value to be larger than the number of fields that a normal client request might include. The number of request header fields used by a client rarely exceeds 20, but this may vary among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation. Optional HTTP extensions are often expressed using request header fields.
This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks. The value should be increased if normal clients see an error response from the server that indicates too many fields were sent in the request.
Web AdministratorECSC-1

SV-32766r2_rule

WA000-WWA064 A22

MEDIUM

The HTTP request header field size must be limited.

Buffer overflow attacks are carried out by a malicious attacker sending amounts of data that the web server cannot store in a given size buffer. The eventual overflow of this buffer can overwrite system memory. Subsequently an attacker may be able to elevate privileges and take control of the server. This Apache directives limits the size of the various HTTP header sizes thereby limiting the chances for a buffer overflow.
The LimitRequestFieldSize directive allows the server administrator to reduce or increase the limit on the allowed size of an HTTP request header field. A server needs this value to be large enough to hold any one header field from a normal client request. The size of a normal request header field will vary greatly among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation. SPNEGO authentication headers can be up to 12392 bytes.
This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks.
Web AdministratorECSC-1

SV-32768r2_rule

WA000-WWA066 A22

MEDIUM

The HTTP request line must be limited.

Buffer overflow attacks are carried out by a malicious attacker sending amounts of data that the web server cannot store in a given size buffer. The eventual overflow of this buffer can overwrite system memory. Subsequently an attacker may be able to elevate privileges and take control of the server. This Apache directives limits the size of the various HTTP header sizes thereby limiting the chances for a buffer overflow.
The LimitRequestLine directive allows the server administrator to reduce or increase the limit on the allowed size of a client's HTTP request-line. Since the request-line consists of the HTTP method, URI, and protocol version, the LimitRequestLine directive places a restriction on the length of a request-URI allowed for a request on the server. A server needs this value to be large enough to hold any of its resource names, including any information that might be passed in the query part of a GET request.
This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks.
Web AdministratorECSC-1

SV-33215r1_rule

WA00500 A22

MEDIUM

Active software modules must be minimized.

Modules are the source of Apache httpd servers core and dynamic capabilities. Thus not every module available is needed for operation. Most installations only need a small subset of the modules available. By minimizing the enabled modules to only those that are required, we reduce the number of doors and have therefore reduced the attack surface of the web site. Likewise having fewer modules means less software that could have vulnerabilities.Web AdministratorDCSQ-1, DCSW-1

SV-33216r1_rule

WA00505 A22

MEDIUM

Web Distributed Authoring and Versioning (WebDAV) must be disabled.

The Apache mod_dav and mod_dav_fs modules support WebDAV ('Web-based Distributed Authoring and Versioning') functionality for Apache. WebDAV is an extension to the HTTP protocol which allows clients to create, move, and delete files and resources on the web server. WebDAV is not widely used, and has serious security concerns as it may allow clients to modify unauthorized files on the web server. Therefore, the WebDav modules mod_dav and mod_dav_fs should be disabled.Web AdministratorECAN-1

SV-33218r1_rule

WA00510 A22

MEDIUM

Web server status module must be disabled.

The Apache mod_info module provides information on the server configuration via access to a /server-info URL location, while the mod_status module provides current server performance statistics. While having server configuration and status information available as a web page may be convenient, it is recommended that these modules not be enabled: Once mod_info is loaded into the server, its handler capability is available in per-directory .htaccess files and can leak sensitive information from the configuration directives of other Apache modules such as system paths, usernames/passwords, database names, etc. If mod_status is loaded into the server, its handler capability is available in all configuration files, including per-directory files (e.g., .htaccess) and may have security-related ramifications.Web AdministratorECAN-1

SV-33220r1_rule

WA00520 A22

MEDIUM

The web server must not be configured as a proxy server.

The Apache proxy modules allow the server to act as a proxy (either forward or reverse proxy) of http and other protocols with additional proxy modules loaded. If the Apache installation is not intended to proxy requests to or from another network then the proxy module should not be loaded. Proxy servers can act as an important security control when properly configured, however a secure proxy server is not within the scope of this STIG. A web server should be primarily a web server or a proxy server but not both, for the same reasons that other multi-use servers are not recommended. Scanning for web servers that will also proxy requests is a very common attack, as proxy servers are useful for anonymizing attacks on other servers, or possibly proxying requests into an otherwise protected network.Web AdministratorECAN-1, ECND-2

SV-33221r1_rule

WA00525 A22

MEDIUM

User specific directories must not be globally enabled.

The UserDir directive must be disabled so that user home directories are not accessed via the web site with a tilde (~) preceding the username. The directive also sets the path name of the directory that will be accessed. The user directories should not be globally enabled since it allows anonymous access to anything users may want to share with other users on the network. Also consider that every time a new account is created on the system, there is potentially new content available via the web site.Web AdministratorIAAC-1

SV-33222r1_rule

WA00530 A22

MEDIUM

The process ID (PID) file must be properly secured.

The PidFile directive sets the file path to the process ID file to which the server records the process id of the server, which is useful for sending a signal to the server process or for checking on the health of the process. If the PidFile is placed in a writable directory, other accounts could create a denial of service attack and prevent the server from starting by creating a PID file with the same name.Web AdministratorECAN-1

SV-33223r1_rule

WA00535 A22

MEDIUM

The score board file must be properly secured.

The ScoreBoardfile directive sets a file path which the server will use for Inter-Process Communication (IPC) among the Apache processes. If the directive is specified, then Apache will use the configured file for the inter-process communication. Therefore if it is specified it needs to be located in a secure directory. If the ScoreBoardfile is placed in a writable directory, other accounts could create a denial of service attack and prevent the server from starting by creating a file with the same name, and or users could monitor and disrupt the communication between the processes by reading and writing to the file.Web AdministratorECAN-1

SV-33226r1_rule

WA00540 A22

MEDIUM

The web server must be configured to explicitly deny access to the OS root.

The Apache Directory directive allows for directory specific configuration of access controls and many other features and options. One important usage is to create a default deny policy that does not allow access to Operating System directories and files, except for those specifically allowed. This is done, with denying access to the OS root directory. One aspect of Apache, which is occasionally misunderstood, is the feature of default access. That is, unless you take steps to change it, if the server can find its way to a file through normal URL mapping rules, it can and will serve it to clients. Having a default deny is a predominate security principal, and then helps prevent the unintended access, and we do that in this case by denying access to the OS root directory. The Order directive is important as it provides for other Allow directives to override the default deny.Web AdministratorIAIA-1, IAIA-2

SV-33213r1_rule

WA00545 A22

MEDIUM

Web server options for the OS root must be disabled.

The Apache Options directive allows for specific configuration of options, including execution of CGI, following symbolic links, server side includes, and content negotiation. The Options directive for the root OS level is used to create a default minimal options policy that allows only the minimal options at the root directory level. Then for specific web sites or portions of the web site, options may be enabled as needed and appropriate. No options should be enabled and the value for the Options Directive should be None.Web AdministratorDCSP-1, ECAN-1

SV-33227r1_rule

WA00550 A22

MEDIUM

The TRACE method must be disabled.

Diagnostics help establish a history of activities, and can be useful in detecting attack attempts or determining tuning adjustments to improve server availability. Trace logs are essential to the investigation and prosecution of unauthorized access to web server software and data. However, in standard production operations, use of diagnostics may reveal undiscovered vulnerabilities and ultimately, to compromise of the data. Because of the potential for abuse, the HTTP Trace method should be disabled.Web AdministratorDCSP-1

SV-33228r1_rule

WA00555 A22

MEDIUM

The web server must be configured to listen on a specific IP address and port.

The Apache Listen directive specifies the IP addresses and port numbers the Apache web server will listen for requests. Rather than be unrestricted to listen on all IP addresses available to the system, the specific IP address or addresses intended must be explicitly specified. Specifically a Listen directive with no IP address specified, or with an IP address of zero’s should not be used. Having multiple interfaces on web servers is fairly common, and without explicit Listen directives, the web server is likely to be listening on an inappropriate IP address / interface that were not intended for the web server. Single homed system with a single IP addressed are also required to have an explicit IP address in the Listen directive, in case additional interfaces are added to the system at a later date.Web AdministratorDCFA-1, DCPP-1

SV-33229r1_rule

WA00560 A22

MEDIUM

The URL-path name must be set to the file path name or the directory path name.

The ScriptAlias directive controls which directories the Apache server "sees" as containing scripts. If the directive uses a URL-path name that is different than the actual file system path, the potential exists to expose the script source code.Web AdministratorECND-1

SV-33219r1_rule

WA00515 A22

MEDIUM

Automatic directory indexing must be disabled.

To identify the type of web servers and versions software installed it is common for attackers to scan for icons or special content specific to the server type and version. A simple request like http://example.com/icons/apache_pb2.png may tell the attacker that the server is Apache 2.2 as shown below. The many icons are used primary for auto indexing, which is recommended to be disabled.Web AdministratorDCSQ-1, DCSW-1

SV-33232r1_rule

WA00547 A22

MEDIUM

The ability to override the access configuration for the OS root directory must be disabled.

The Apache OverRide directive allows for .htaccess files to be used to override much of the configuration, including authentication, handling of document types, auto generated indexes, access control, and options. When the server finds an .htaccess file (as specified by AccessFileName) it needs to know which directives declared in that file can override earlier access information. When this directive is set to None, then .htaccess files are completely ignored. In this case, the server will not even attempt to read .htaccess files in the file system. When this directive is set to All, then any directive which has the .htaccess Context is allowed in .htaccess files.Web AdministratorDCSP-1

SV-33236r1_rule

WA00565 A22

MEDIUM

HTTP request methods must be limited.

The HTTP 1.1 protocol supports several request methods which are rarely used and potentially high risk. For example, methods such as PUT and DELETE are rarely used and should be disabled in keeping with the primary security principal of minimize features and options. Also since the usage of these methods is typically to modify resources on the web server, they should be explicitly disallowed. For normal web server operation, you will typically need to allow only the GET, HEAD and POST request methods. This will allow for downloading of web pages and submitting information to web forms. The OPTIONS request method will also be allowed as it is used to request which HTTP request methods are allowed.Web AdministratorDCSP-1